Production of petrochemical feedstocks and products using a fuel cell

ABSTRACT

A method of producing petrochemicals using a hydrocarbon fuel cell includes the steps of operating the fuel cell to produce electricity, thermal energy, and one or more exhaust stream, the one or more exhaust stream comprising at least a carbon-containing gas and water, reacting at least a portion of the exhaust stream with the reactant stream of natural gas to produce one or more petrochemical streams in a reactor, and heating one or more reactants using at least a portion of at least one of the electricity and the thermal energy.

FIELD

This relates to a method that recovers and converts exhaust streams froma fuel cell to produce petrochemical feedstocks and products, which maybe done at near zero GHG emissions.

BACKGROUND

The production of petrochemicals is well understood, and typicallyinvolves energy intensive catalytic processes. The major development inthese processes is on catalyst research to improve operating conditionsand increase production efficiencies. The awareness of climate changechallenges industry to reduce GHG emissions and to develop technologiesthat converts carbon dioxide into products. Dry methane reformingtechnology is the most suitable technology for converting CO₂ into newproducts by reacting it with natural gas to generate a syngas mixture ofCO and H₂. The obstacles for dry methane reforming include its potentialfor carbon formation due to the lower H/C ratio and via the Boudouardreaction, it also has a less favourable thermodynamics that makes itmore difficult to achieve a high rate of conversion for the reactants.These obstacles can be alleviated by specially designed catalysts,optimizing the CO₂:CH₄ ratio and operating conditions. The challenges indry methane processing have been the development of a catalyst that isresistant to coke fouling and a high quality supply of carbon dioxide athigh temperatures. The National Research Labs of Canada (NRCAN) hasdeveloped a dry methane reforming catalyst that is resistant to cokefouling. EPI has developed a process to recover a high quality stream ofcarbon dioxide from a fuel cell anode exhaust stream and deliver it athigh temperatures for the dry reforming of methane. Present dry methanereforming processes require carbon dioxide recovery units that areenergy intensive processes in recovering and preparing carbon dioxidefor dry methane reforming.

Another commonly produced petrochemical is methanol, which is a largevolume commodity chemical. The production of methanol is wellunderstood, and is generally considered an energy intensive, catalyticprocess. Industrial methanol is produced mainly by indirect liquefactionof natural gas. The indirect liquefaction process is done in two steps;reforming natural gas into synthesis gas followed by conversion intomethanol. Both of these steps are catalytic processes, thereforeresearch on catalysts to improve reactor operating conditions andproduction efficiencies are paramount. One major issue in researchdevelopment is the curtailment of costs for producing synthesis gas fromnatural gas, which accounts for about 60% of the costs in the productionof methanol. The three main routes to convert natural gas to syngas aresteam reforming (SMR), partial oxidation (PDX) and auto thermalreforming (ATR). The most widely used technology to produce syngas formethanol synthesis is steam reforming. The overall methane steamreforming is highly endothermic, with the heat required by the processreaction generally being supplied by burning natural gas. In the partialoxidation process, natural gas is reacted with insufficient oxygen. Thisreaction is exothermic and is conducted at high temperatures, typicallygreater than 1200° C. Modern methanol plants use auto thermal reforming,which combines steam reforming with partial oxidation, where heatproduced by the exothermic partial oxidation reaction is consumed by theendothermic steam reforming reaction. This process can be done inseparate reactors or in a single reactor by adding water and oxygen. Thedrawback to this process is the large production of carbon dioxide,which may be sequestered or vented into the atmosphere. The productionof carbon dioxide and the awareness of climate change challengesindustry to minimize greenhouse emissions, minimize energy consumptionand enhance syngas processes to produce methanol.

SUMMARY

The present method was developed with a view to recover thermal energyand fuel cell exhaust streams to produce petrochemical feedstocks. Theprocess added benefit is the recovery and conversion of carbon dioxide,(a GHG emission gas) to produce valuable products.

According to an aspect, the presently described process allows carbondioxide to be recovered and converted into value added products using adry methane reforming process to convert a mixture of natural gas andcarbon dioxide into a syngas product of carbon monoxide and hydrogen,which is a premium feedstock in the production of petrochemicals. Thepresent system and method may also be used to produce a wide spectrum ofother petrochemicals from two components, natural gas and atmosphericair, at near zero GHG emissions. Natural gas and atmospheric air may beused as inputs into a fuel cell, which produces energy and components inits exhaust streams that may then be used to produce petrochemicalsefficiently and economically. Typically, there will be a natural gasfuel stream to the fuel cell, and a reactant stream to the downstreamreaction to produce petrochemicals. In one aspect, a fuel cell anodecarbon dioxide exhaust stream is cooled, separated, condensed,recovered, pumped, heated and mixed with natural gas for the catalyticprocess of dry reforming. The process thus allows for the recovery of awaste stream and its thermal energy to produce valuable reactants.

According to an aspect, there is provided a process that recoversexhaust streams and thermal energy from a fuel cell and provideselectrical energy for the production of petrochemicals at near zero GHGemissions.

The process of generating power with a natural gas fuel cell differsfrom standard power generation plants that use natural gas. In a fuelcell, natural gas is consumed at the anode through an electrochemicalreaction that produces electricity and a hot exhaust stream of gases,mainly water vapor and carbon dioxide, whereas in combustion based powergeneration plants, the exhaust stream is mainly nitrogen oxides, withwater and carbon dioxide being minor components by mass and or volume inthe combustion exhaust stream. The fuel cell anode exhaust stream ismainly carbon dioxide and water vapor, which combined is less than 75%of the exhaust mass flow rate of power generation combustion process.The concentrated fuel cell anode exhaust stream with its thermal energyis an ideal source to recover and convert carbon dioxide into valueadded products. The anode exhaust stream is a by-product of producingelectricity with a fuel cell. The thermal energy of this anode exhaustgas stream is typically partially recovered in cogeneration processes tosupply heat before the exhaust gas is released into the atmosphere.

The proposed system and method may be used recover the fuel cell exhauststreams thermal energy and its components for other uses.

According to another aspect, the process may include some or all of thefollowing features:

-   -   Power generation by chemical reaction of natural gas in a fuel        cell.    -   No or reduced GHG emissions released into the atmosphere, as the        fuel cell anode exhaust stream and its thermal energy are        recovered to produce water and carbon dioxide, where the exhaust        stream may be further mixed with natural gas as a feedstock,        such as for a tri-reforming methane (TRM) unit.    -   Production of water, the anode chemical reaction by        stoichiometry produces 2.25 Kg of water per Kg of methane.    -   Production of carbon dioxide, the anode chemical reaction by        stoichiometry produces 2.75 Kg of carbon dioxide per Kg of        methane.    -   Recovering a fuel cell anode exhaust stream thermal energy to        heat; carbon dioxide, water and natural gas.    -   Recovering a fuel cell cathode exhaust stream thermal energy to        heat steam, natural gas and atmospheric air.    -   Recovery and efficient production of carbon dioxide, water and        nitrogen.    -   Conversion of carbon dioxide through dry reforming or        tri-reforming.    -   Conversion of water into hydrogen and oxygen through        electrolysis.    -   Conversion of nitrogen into ammonia through catalytic processes.    -   A method where a fuel cell is both an energy provider (thermal        and electrical) and a producer of highly concentrated streams of        carbon dioxide, water and nitrogen for other petrochemical uses,        such as to produce syngas, methanol, or other petrochemicals.        The streams may be separated, or used directly in a mixed state        as an exhaust stream.    -   A method to produce petrochemicals at zero or near zero GHG        emissions. It will be understood that the actual GHG emissions        will depend on the process as a whole, such as the composition        of the exhaust streams, the products being produced, the        reactions used to produce the products, and the efficiency        and/or overall design of the equipment used.

According to a further aspect, the process may produce electricity foruse and or export from a fuel cell and recovers the thermal energy andcomponents of its exhaust streams for other uses. The fuel cell may bevarious types of fuel cell such as a molten carbonate, a solid oxide orphosphoric acid. The process for the production of dry reformingfeedstock may comprise:

-   -   First, reducing the natural gas pressure supply to the tri        reformer and fuel cell anode through an expander generator to        produce electricity and a refrigerant natural gas stream.    -   Second, the refrigerant natural gas fuel stream enters a series        of heat exchangers in a counter-current flow with the gaseous        anode exhaust stream to cool and condense the exhaust water and        carbon dioxide components.    -   Third, the natural gas supply stream gives up its generated        coolth energy in a series of counter-current heat exchangers        cooling and condensing the anode exhaust gaseous stream and        simultaneously preheating the natural gas to the anode exhaust        temperature.    -   Fourth, the now-heated natural gas supply stream enters the fuel        cell anode where it is converted by steam reforming and        electrochemical reactions into electricity and produces a high        temperature anode exhaust gas stream that is mainly carbon        dioxide and water.    -   Fifth, the high temperature anode exhaust gas stream is        pre-cooled in the counter-current flow heat exchanger with the        natural gas supply stream.    -   Sixth, the anode exhaust gas stream is further cooled in a        counter-current flow heat exchanger by the recovered and        pump-pressurized carbon dioxide stream.    -   Seventh, the condensed water fraction of the anode exhaust gas        stream is separated in a gas/liquid separator and the separated        anode exhaust gaseous carbon dioxide stream is routed for        further cooling in a counter-current heat exchanger with the        recovered liquid carbon dioxide stream.    -   Eighth, the anode exhaust gaseous carbon dioxide stream is        further cooled in a counter-current heat exchanger with a cold        carbon dioxide gaseous stream.    -   Ninth, the anode exhaust gaseous carbon dioxide stream is        further cooled in a counter-current heat exchanger with the        refrigerant natural gas supply stream to cool and condense a        portion of the anode exhaust carbon dioxide and passed through a        carbon dioxide separator.    -   Tenth, the recovered liquid carbon dioxide stream is pumped and        pressurized and passed through a heat exchanger in a        counter-current flow with the anode exhaust stream to its        maximum temperature recovery.    -   Eleventh, the recovered water stream is pumped and pressurized        and then passed through a heat exchanger in a counter-current        flow with the anode exhaust stream.    -   Twelfth, the gaseous carbon dioxide stream from the carbon        dioxide separator is mixed with fresh air and catalysed in a        catalytic oxidizer to heat this oxidant stream up to fuel cell        cathode temperature. The cathode consumes oxygen from the air        and the carbon dioxide to produce a carbonate ion that is        transferred through the fuel cell electrolyte layer to the anode        to react with the anode hydrogen producing; water, carbon        dioxide and electricity.    -   Thirteenth, a portion of the recovered water is routed to        produce steam in a counter-current flow heat exchanger with the        cathode exhaust gas stream, and the steam is supplied to a        reformer at the anode.    -   Fourteenth, the high temperature cathode exhaust gas stream is        pre-cooled in a counter-current flow heat exchanger by a natural        gas stream flowing to the fuel cell anode.    -   Fifteenth, the cathode exhaust stream is further cooled in a        counter-current flow heat exchanger by steam flowing to the fuel        cell anode.    -   Sixteenth, the cathode exhaust stream is cooled further in a        counter-current flow heat exchanger by atmospheric air supply        flowing to the fuel cell cathode.    -   Seventeenth, using electricity generated by the fuel cell to        power electric furnaces or devices to meet energy requirements        of the petrochemical-production process.    -   Eighteenth, a fuel cell is operated to produce electricity,        water and carbon dioxide. The fuel cell anode exhaust recovered        carbon dioxide and water, thermal and electrical energy combined        with additional natural gas produces methanol through a tri        reforming methane process at near zero GHG emissions.

According to a further aspect, the process may produce electricity foruse and or export from a fuel cell and recovers the thermal energy andcomponents of its exhaust streams for other uses. The fuel cell may bevarious types of fuel cell such as a molten carbonate, a solid oxide orphosphoric acid. The process for the production of dry reformingfeedstock may comprise:

-   -   First, reducing the natural gas pressure supply to the tri        reformer and fuel cell anode through an expander generator,        producing electricity and a refrigerant natural gas stream.    -   Second, pre-heating the refrigerant natural gas fuel supply to        the tri reformer and fuel cell by heat exchange with streams in        the TRM unit.    -   Third, introducing the heated natural gas supply stream to the        fuel cell anode where it is converted by steam reforming and        electrochemical reactions into electricity and a high        temperature anode exhaust gas stream of mainly carbon dioxide        and steam.    -   Fourth, routing a portion of the anode exhaust stream to the        cathode where oxygen supplied from atmospheric air and the        carbon dioxide in the anode exhaust stream react to produce a        carbonate ion which is transferred through the fuel cell        electrolyte layer to the anode to react with the anode hydrogen        producing; steam, carbon dioxide and electricity.    -   Fifth, mixing the remaining high temperature anode exhaust gas        stream with natural gas and heated to TRM unit process pressure        and temperature.    -   Sixth, pre-cooling the high temperature cathode exhaust gas        stream in a counter-current flow heat exchanger by natural gas        stream to the fuel cell anode.    -   Seventh, cooling the cathode exhaust stream further in a        counter-current flow heat exchanger by steam to the fuel cell        anode.    -   Eighth, cooling the cathode exhaust stream further in a        counter-current flow heat exchanger by atmospheric air supply to        the fuel cell cathode.    -   Ninth, if required or preferred, using electricity generated by        the fuel cell in electric furnaces or electric devices to meet        thermal energy requirements of the TRM unit.    -   Tenth, operating the fuel cell to produce electricity, carbon        dioxide and steam. The fuel cell anode exhaust stream will be        made up of mainly carbon dioxide and steam, thermal and        electrical energy combined with additional natural gas produces        methanol in a TRM unit at near zero GHG emissions.

In one aspect, the process may use a high temperature anode exhauststream from a fuel cell that is mainly carbon dioxide and steam with alarge amount of thermal energy, which is mixed with natural gas as afeed source to a TRM unit to produce petrochemicals, such as methanol.

The natural gas may be used as a refrigerant to help condense andseparate water and/or carbon dioxide from the anode exhaust stream priorto being used to produce petrochemicals. Various approaches arepossible. For example, the natural gas may be expanded to make use ofthe Joules-Thompson effect in a J-T valve, a turbo expander, agenerator, etc. The cooling capacity of the natural gas may be increasedby pressurizing the stream of natural gas and then cooling thepressurized stream in an air cooled fan prior to being expanded, or bypassing the natural gas through an external refrigeration plant. As afurther possibility, natural gas may be supplied as liquid natural gas(LNG), which is at cryogenic temperatures. As the natural gas is used asa refrigerant, it is heated by the stream it is cooling, and may beheated toward a target temperature that is required for the downstreamreactions to produce petrochemicals.

As will hereinafter be described, the present method may operate at anysite where natural gas is available, or may be made available. Therecovered components of carbon dioxide, water and nitrogen may beconverted into petrochemical feedstocks and or products. Typically, therecovered components will be recovered as a high temperature anodeexhaust stream from a fuel cell in vapour form. If producing methanol,these components may then be mixed with natural gas and reacted in a TRMunit. The electricity produced in the fuel cell provides the motive andthermal energy requirements of petrochemical processes. This processprovides for the production of petrochemicals at near zero GHGemissions.

As will hereinafter be further described, there is provided a method toproduce petrochemical products and feedstocks from fuel cell exhauststreams, which includes a natural gas supply stream to a dry reformerand a fuel cell, first reducing the natural gas pressure through a gasexpander/generator producing a refrigerant natural gas stream andelectricity. The refrigerant natural gas stream is pre-heated in aseries of counter-current heat exchangers to cool and condense carbondioxide and water from a fuel cell anode exhaust stream. The heated fuelcell natural gas stream is further heated and fed to the fuel cell anodewhere first it is steam reformed to produce hydrogen and carbon dioxide,the hydrogen is further reacted with a carbonate ion to produce water,carbon dioxide and electricity. The anode hot exhaust gas stream, iscooled, condensed, separated, recovered, pressurized and heated forother process uses. The cathode exhaust stream of mainly nitrogen, iscooled, separated and recovered for other uses. The objective of theinventive process is to recover and convert the fuel cell exhaust streamcomponents into products at near zero GHG emissions. In one example, theprocess may be used to produce natural gas using a high temperatureanode exhaust stream of primarily carbon dioxide and steam; the naturalgas stream may be pre-heated by process streams in a TRM unit; and hightemperature anode exhaust gas stream may be mixed with natural gas andconditioned to the TRM unit at optimum operating pressure andtemperature conditions to produce methanol.

According to an aspect, there is provided a method of producingpetrochemicals using a hydrocarbon fuel cell, comprising the steps ofoperating the fuel cell to produce electricity, thermal energy, and oneor more exhaust stream, the one or more exhaust stream comprising atleast a carbon-containing gas and water, reacting at least a portion ofthe exhaust stream with the reactant stream of natural gas to produceone or more petrochemical streams in a reactor, and heating one or morereactants using at least a portion of at least one of the electricityand the thermal energy.

According to other aspects, the carbon-containing gas and the water maybe produced from an anode of the hydrocarbon fuel cell, the one or moreexhaust streams may further comprise a nitrogen-containing gas producedfrom a cathode of the hydrocarbon fuel cell, at least a portion of thethermal energy may be carried by the one or more exhaust streams, thethermal energy may be used to preheat the reactant stream of naturalgas, the one or more petrochemical streams may comprise one or more of agroup consisting of: synthesis gas, methanol, ammonia, urea, polymers,prepolymers, hydrocarbon fuels, acetic acid, and glycol, the method mayfurther comprise the step of separating the carbon-containing gas andthe water into separate streams using heat exchangers and phaseseparators, the reactant stream of natural gas may comprises methane,ethane, propane, or combinations thereof, the reactant stream of naturalgas and the at least a portion of the exhaust stream may bepreconditioned in heat exchangers using the thermal energy of the energystream, the method may further comprise the step of powering at leastone of material handling equipment and heating equipment of the reactor,the fuel cell may be powered by a fuel stream of natural gas, and thereactant stream of natural gas may comprise a slipstream of the fuelstream of natural gas, substantially all of the carbon in thecarbon-containing gas may be consumed in the reaction, and the reactionmay comprise two or more reactions conducted in parallel or in series.

According to an aspect, there is provided a method of manufacturingpetrochemicals from exhaust streams of a fuel cell by condensing,recovering, pumping and heating exhaust streams of carbon dioxide, waterand nitrogen while producing electrical and thermal energy, the methodcomprising the steps of providing a fuel cell having an anode and acathode, a series of fluid streams connected to the fuel cell, and aplurality of heat exchangers that heat and cool selected fluid streams,supplying natural gas to the fuel cell in a fuel stream and to apetrochemical unit in a reactant stream connected to a petrochemicalproduction unit, heating the fuel stream of natural gas in one or moresecond heat exchangers and mixing the heated fuel stream with steam atan anode of the fuel cell, pre-heating an air stream to meet atemperature requirement of a cathode of the fuel cell, cooling andseparating the anode exhaust stream to produce a stream of condensedsteam, a stream of condensed carbon dioxide, and a remaining anodeexhaust stream, the remaining anode exhaust stream comprising unreactedresiduals and carbon dioxide, the remaining anode exhaust stream beingmixed with the air stream prior to being communicated to the cathode ofthe fuel cell, pressurizing and heating the stream of condensed carbondioxide to achieve an operating pressure and temperature of one or morepetrochemical production units, pressurizing and heating a first portionof the stream of condensed steam to produce the steam that is mixed withthe heated fuel stream at the anode of the fuel cell, and pressurizingand heating a second portion of the stream of condensed steam topetrochemical units operating pressures and temperatures of one or morepetrochemical production units

According to other aspects, the remaining anode exhaust stream may becompressed to meet desired operations properties for the fuel cell, themethod may further comprise the step of cooling the pressurized naturalgas produce a refrigerant stream of natural gas that is used to cool theanode exhaust stream by passing the pressurized natural gas through agas expander/generator to produce electricity or through aJoules-Thompson valve, the natural gas supply may comprise liquidnatural gas (LNG), the method may further comprise the step of adding anexternal source of one or more of carbon dioxide, water and nitrogen toone or more petrochemical production units, the natural gas may bediverted from an existing gas processing plant or straddle gas plant,and the electricity generated in the fuel cell may supply motive powerand thermal power to the one or more petrochemical production units.

According to an aspect, there is provided a tri-reforming methane (TRM)process, which is a method of direct methane to methanol conversion bymixing natural gas, carbon dioxide and water, that provides analternative method for direct production of synthesis gas with desirableH₂/CO ratios by reforming methane or natural gas using recovered andconditioned exhaust streams from a fuel cell. This TRM process may beused to deliver high purity streams of carbon dioxide and water atdesirable pressures and temperatures from a fuel cell to meet theoptimum conditions for tri-reforming with methane or natural gas.Moreover, additional motive and thermal energy for the process may beprovided by electricity produced from the fuel cell, thus enabling theproduction of methanol at or near zero GHG emissions. These processdescribed herein may be used to help recover and convert carbon dioxideinto value added products, and therefore reducing the amount of carbondioxide vented to atmosphere.

According to an aspect, the TRM process uses a fuel cell to provide boththe reactants and energy to produce methanol at near zero GHG emissions.Moreover, the proposed process enables the production of methanol fromnatural gas and atmospheric air at near zero GHG emissions. A fuel cellmay be beneficially used to produce energy and components from itsexhaust streams to efficiently and economically produce methanol. In thedisclosed process, a fuel cell anode exhaust stream that contains carbondioxide and water is cooled, separated, recovered, pumped, heated andmixed with natural gas for the catalytic process of tri methanereforming.

As will hereinafter be further described, there is provided a method toproduce methanol by mixing methane with recovered carbon dioxide andwater from a fuel cell anode exhaust stream, which includes a supply ofnatural gas supply stream to a fuel cell and to a tri reformer reactor.According to an aspect, the method includes, first, routing two streamsof natural gas; one to supply the fuel cell, and the other to supply themethane reformer. The natural gas pressure is reduced through gasexpanders/generators to produce refrigerant natural gas streams andelectricity. The refrigerant natural gas streams are pre-heated in aseries of counter-current heat exchangers that also cool and condensecarbon dioxide and water from a fuel cell anode exhaust stream. Theheated fuel cell natural gas stream is further heated and fed to thefuel cell anode where it is steam reformed to produce hydrogen andcarbon dioxide, and the hydrogen is further reacted with a carbonate ionin the fuel cell to produce water, carbon dioxide and electricity. Theanode exhaust gas stream, which is hot, is, in sequence, cooled,condensed, separated, recovered, pressurized and heated for mixing andreacting with methane to produce methanol. The cathode exhaust stream ofmainly nitrogen, is cooled and recovered for other uses or released intothe atmosphere. The objective of the process is to recover and convertthe fuel cell anode exhaust stream of carbon dioxide and water to mixand react with methane or natural gas to produce methanol.

According to an aspect, there is provided a method of producingpetrochemicals using a hydrocarbon fuel cell, comprising the steps ofoperating the fuel cell to produce one or more exhaust stream, capturingat least one of the exhaust streams, mixing the captured exhaust streamswith a stream of natural gas, and reacting the captured exhaust streamand the stream of natural gas to produce one or more petrochemicalstreams in a reactor.

According to other aspects, the exhaust stream may comprise at least acarbon-containing gas, at least water, or at least a nitrogen containinggas, at least a portion of the exhaust stream may be produced from ananode of the hydrocarbon fuel cell, the one or more petrochemicalstreams may comprise one or more of a group consisting of: synthesisgas, methanol ammonia, urea, polymers, prepolymers, hydrocarbon fuels,acetic acid, and glycol, the stream of natural gas may comprise methane,ethane, propane, or combinations thereof, and substantially all of thecarbon in the carbon-containing gas may be consumed in the reaction.

According to an aspect, there is provided a method of producing methanolthrough the operation of a fuel cell, comprising the steps of providinga pressurized natural gas stream, diverting at least a portion of thepressurized natural gas stream as a natural gas fuel stream to a fuelcell and at least a portion as a reactant natural gas stream to amethanol production unit, expanding at least a portion of thepressurized natural gas stream to decrease the pressure of thepressurized natural gas stream to produce a refrigerant natural gassupply stream, operating the fuel cell to produce energy, an anodeexhaust stream comprising carbon dioxide and water, and a cathodeexhaust stream, passing the heated anode exhaust stream through a seriesof heat exchangers and separators to produce a stream of condensedwater, a stream of condensed carbon dioxide, and a stream of gaseouscarbon dioxide, heating the natural gas fuel stream for mixing withsteam and reforming at a fuel cell anode, mixing an air stream with aportion of the carbon dioxide from the anode exhaust stream to form afuel cell air supply, pre-heating the fuel cell air supply to meet anoperating temperature of the fuel cell cathode, pressurizing and heatingthe stream of condensed carbon dioxide to a reactor operating pressureand temperature, pressurizing and heating a first portion of the streamof condensed water to produce steam for mixing with the heated naturalgas fuel stream for the fuel cell anode reformer, and pressurizing andheating a second portion of the stream of condensed water to the reactoroperating pressure and temperature.

According to other aspects, the anode exhaust stream may compriseunreacted residuals, the unreacted residuals being mixed with the airstream to form the fuel cell air supply, the unreacted residuals may becompressed to meet desired operations properties within a catalyticoxidizer, the at least a portion of the pressurized natural gas may beexpanded using a Joules-Thompson valve or an expander/generator, atleast a portion of the pressurized natural gas may be furtherpressurized to increase a cooling capacity of the natural gas supplystream, a refrigeration plant may be supplied to increase therefrigeration properties of the refrigerant natural gas supply stream,the pressurized natural gas stream may comprise liquid natural gas(LNG), an external source of carbon dioxide may be added to at least oneof the stream of condensed carbon dioxide and the stream of gaseouscarbon dioxide, an external source of treated water may be added to thestream of condensed water produced from the anode exhaust stream, thenatural gas may be diverted from an existing gas processing plant or toa straddle gas plant, the energy generated by the fuel cell may supplymotive power to the methanol production unit and surplus thermal power,substantially all of the carbon in the anode exhaust stream may beconsumed, the fuel cell energy may be combined with the anode exhauststream comprising carbon dioxide and water to generate methanol at themethanol production unit, and each of the reactant stream of naturalgas, the stream of condensed carbon dioxide, and the stream of condensedwater may be flow controlled and temperature controlled to meet optimumreaction operating conditions before and after mixing.

According to an aspect, there is provided a method of using a fuel cellanode exhaust stream consisting mainly of carbon dioxide and steam thatis mixed with a supply of natural gas, the mixture being conditioned toan operating temperature and pressure sufficient to react in a TRM unitto produce methanol at near zero GHG emissions. The method comprises thesteps of: providing a pressurized natural gas supply stream to a fuelcell and to a methanol production unit; providing a gas expander orexpansion generator to produce electricity and a refrigerant natural gassupply stream as per the Joules Thompson effect while decreasingpressure of a gas stream; providing one or more cooling streams to theTRM unit; providing a jet pump or venturi driven by a pre-heated naturalgas supply provided to a methanol unit that draws and mixes with thecathode exhaust stream; providing a pre-heated air stream for mixingwith a re-circulated cathode exhaust stream to supply carbon dioxide tothe fuel cell cathode for the production of carbonate ion; providing afuel cell that generates power and is fueled by natural gas; providingan on-line electrical heater to achieve an operating temperature priorto feeding the mixture to the TRM unit.

In other aspects, the method may comprise one or more of the followingfeatures, alone or in combination: the generators/expanders may beemployed to reduce natural gas pressure supply to the fuel cell and TRMunit; the jet pump or venturi may be employed to draw in the cathodeexhaust stream and mix with natural gas supply to the TRM unit;Joules-Thompson valves may be employed in lieu of expanders/generators;the natural gas supply may be boosted to increase the pressure of thenatural gas supply pressure to generators/expanders; the natural gassupply may be liquid natural gas (LNG) in lieu of a pressurized naturalgas supply; an external source of carbon dioxide may be added to the TRMnatural gas supply/cathode exhaust mixer; an external source of steammay be added to the TRM natural gas supply/cathode exhaust mixer; theproposed process may be located at any natural gas supply infrastructureor supplied with another source of natural gas, such as liquid naturalgas; the electricity generated in the fuel cell may supply both motivepower to the proposed TRM unit as well the process thermal powerrequired such as electric furnaces and or electrical on-line heaters;the method may produce methanol at near zero GHG emissions by directmixing of a stream from a fuel cell anode exhaust stream; a fuel cellanode exhaust stream of mainly carbon dioxide and steam may be directlymixed with a supply of natural gas to produce methanol; energy from thefuel cell, such as electrical and thermal, may be combined withco-products of carbon dioxide and steam to provide the means to meetproven and commercial methanol processes inputs to generate methanol atnear zero GHG emissions; the reactant streams of natural gas and fuelcell anode exhaust may be controlled to pressure and temperature meetoptimum reaction operating conditions in the TRM unit; a mixture of thereactant streams of natural gas with a fuel cell anode exhaust streammay be controlled to pressure and temperature optimum reaction operatingconditions in catalytic or non-catalytic reactors units; a fuel cellanode exhaust stream may be employed as reactants in petrochemicalsprocesses; a fuel cell cathode exhaust stream may be mixed with a supplyof natural gas or other hydrocarbons gaseous streams such as ethane,propane, butane, etc. and conditioned to pressure and temperature toother catalytic or non-catalytic processes to produce other products.

In other aspects, the features described above may be combined togetherin any reasonable combination as will be recognized by those skilled inthe art.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features will become more apparent from the followingdescription in which reference is made to the appended drawings, thedrawings are for the purpose of illustration only and are not intendedto in any way limit the scope of the invention to the particularembodiment or embodiments shown, wherein:

FIG. 1 is a schematic diagram of a preferred fuel cell exhaust streamrecovery of its water, carbon dioxide, nitrogen and thermal energy forother uses such as carbon dioxide for the dry reforming of methane.

FIG. 2 is a schematic diagram of an alternative natural gas pressureexpansion at two different operating pressures. One gas expander reducesthe pressure to meet fuel cell pressure requirements while the other gasexpander reduces the gas pressure to meet a catalytic reactor pressurerequirements.

FIG. 3 is a schematic diagram of a method to produce a syngas of carbonmonoxide and hydrogen by using a carbon dioxide stream produced in thefuel cell with natural gas.

FIG. 4 is a schematic diagram of a method to produce methanol by usingand combining streams of carbon dioxide and steam produced in the fuelcell with natural gas.

FIG. 5 is a schematic diagram of methods to produce variouspetrochemical feedstocks and products from streams of carbon dioxide,nitrogen and water produced at a fuel cell supported with electricalenergy produced by the fuel cell to meet both motive and thermal energyprocess needs. Hence a fuel cell is both a provider of energy andreactants products.

FIG. 6 is a schematic diagram of the methods to produce variouspetrochemical feedstocks and products from streams of carbon dioxide,nitrogen and water produced at a fuel cell supported with electricalenergy produced by the fuel cell to meet both motive and thermal energyprocess needs. Hence a fuel cell is both a provider of energy andreactants products at near zero GHG emissions.

FIG. 7 is a schematic diagram of a method to produce petrochemicalsusing a carbon dioxide stream produced in the fuel cell with naturalgas.

FIG. 8 is a schematic diagram of a fuel cell and tri reforming methanereactor process, showing the recovery of carbon dioxide, water andthermal energy from a fuel cell anode exhaust stream to mix and reactwith natural gas to produce methanol.

FIG. 9 is a variation of the process in FIG. 8 , where the reactantstreams temperature and flow ratios are individually controlled beforemixing, followed by the temperature optimization of the mixture toreaction temperatures in a on-line electric heater.

FIG. 10 is a variation of the process in FIG. 8 , where a natural gasfeed supply is compressed in order to meet the required conditions of atri-reforming methane (TRM) reactor.

FIG. 11 is a schematic diagram of a fuel cell and TRM reactor process,showing a fuel cell anode exhaust stream mixing with natural gas, heatedand reacted in a TRM unit to produce methanol.

FIG. 12 is a variation of the process diagram in FIG. 11 where theprocess is operated under vacuum.

FIG. 13 is a variation of the process diagram in FIG. 11 and FIG. 12where the process is operated under a balanced pressure.

FIG. 14 is a variation of the process diagram in FIG. 11 where theprocess where natural gas supply pressure letdown is through JT valvesversus gas expanders/generators.

FIG. 15 is a variation of the process diagram in FIG. 11 where theprocess where natural gas supply pressure is further boosted beforepressure letdown gas expanders/generators.

FIG. 16 is a variation of the process diagram in FIG. 15 where theprocess where natural gas supply to the TRM unit is at natural gassupply pressure.

FIG. 17 is a variation of the process diagram in FIG. 12 where thecathode exhaust stream to the mixer is pressure boosted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The method will now be described with reference to FIG. 1 through 17 .

As described herein, the method was developed with a view to recover andconvert exhaust streams from a fuel cell into petrochemical feedstocksand products, preferably at near zero GHG emissions, although the actualemissions will depend on the process used in practice. The process usesa different approach to recover thermal energy from an exhaust stream tofirst condense its components and then use the same thermal energy topreheat and produce petrochemical feedstocks and products. The systemhere described separates, recovers and converts a fuel cell concentratedhot exhaust gas streams into petrochemical feedstocks and products atnear zero GHG emissions. The system may also mix the hot exhaust streamwith natural gas and condition the mixture to achieve pressures andtemperatures at which a reaction may occur in a tri-reforming methane(TRM) unit.

As used herein, the term petrochemicals is intended to refer to productsthat are produced using a hydrocarbon as the input, in this case,natural gas. These products may be intermediate products, i.e., that areused to produce other products, or final products. This includes a widerange of petrochemical feedstocks or products that may be made usingnatural gas and the fuel cell exhaust streams as the reactants. Thenatural gas used as one of the reactants will generally be methane(CH₄), but other heavier hydrocarbons may also be used, such as ethane(C₂H₆), propane (C₃H₈), etc. The natural gas may be in various forms,such as rich natural gas, which is a mixture of methane and heavierhydrocarbons, liquid natural gas (LNG), pressurized liquid natural gas(PLNG), compressed natural gas (CNG), and the like.

The method and apparatus described herein may also take advantage of thethermal energy and electricity that is produced by the fuel cell to helpfuel the petrochemical reaction. Examples of petrochemicals that may beproduced include synthesis gas (or syngas), methanol, ammonia, urea,polymers, prepolymers, hydrocarbon fuels, acetic acid, glycol, etc., andexamples of how these petrochemicals may be produced are describedbelow. However, it will be understood that other types of petrochemicalsmay also be produced, using the various inputs described herein asreactants. In some circumstances, additional reactants may need to besupplied to supplement those available from the natural gas and from thefuel cell exhaust streams.

The present method may be used to convert the recovered exhaust streamsof water, carbon dioxide and nitrogen into petrochemical feedstocks andproducts. This method recovers the exhaust gas streams of a fuel celltypically discharged into the atmosphere as a by-product of powergeneration to produce petrochemical feedstock and products at near zeroGHG emissions. The applications of the methods described herein should,therefore, be considered examples.

Referring to FIG. 1 an example of a method of recovering a fuel cellanode exhaust stream of water and carbon dioxide and its thermal energyto produce a carbon dioxide stream for dry reforming processes is shown.Fuel cells such as the Direct Fuel Cell (DFC) manufactured by Fuel CellEnergy in the USA have been available since 2003. The largest DFC powergeneration plant is a 59 MW built in South Korea. A major advantage of aDFC power generation plant versus standard power generation combustionprocess plants is the separated and highly concentrated mass flow rateof the exhaust gas streams allowing for ease of recovery and userelative to a combustion process.

Natural gas is delivered from a main transmission pipeline throughstream 1 and enters an expander/generator 2 to reduce the maintransmission pipeline pressure to meet fuel cell inlet pressure stream3, during which the temperature of stream 3 is decreased from 1.5 to 2degrees Celsius for every 15 psi pressure drop. The cooler natural gasstream 3 enters heat exchanger 4 to be heated by, and give up its coolthenergy to, stream 58. The natural gas stream 5 is further heated in heatexchanger 6 by cooling stream 38. Natural gas stream 7 is further heatedin heat exchanger 8 by cooling anode exhaust stream 31. The heatednatural gas stream 9 is split into streams 10 and 11. The heated naturalgas stream 11 is routed to other units, as shown in FIG. 3 . A portion10 a of natural gas stream 10 may be routed to catalytic air pre-heater23 to combust any unreacted hydrocarbons or hydrogen in stream 63. Theremaining portion 10 b of stream 10 is the natural gas feed to the fuelcell 70, and is further heated in heat exchanger 12 by fuel cell cathodeexhaust stream 26. The heated fuel cell gas stream 13 is mixed withsteam stream 45, and enters the fuel cell anode section 47, throughstream 46. At fuel cell anode 47, the natural gas/steam stream 46 isfirst reformed to produce hydrogen and carbon dioxide, the hydrogenthrough an electrochemical reaction with a carbonate ion produced incathode 25 and transferred through an electrolyte layer to the anode 47,produces electricity stream 69, and a hot anode exhaust stream 31. Thecarbonate ion produced in cathode 25 and transferred through anelectrolyte layer into anode 47 is converted back to carbon dioxide inthe electrochemical reaction. The main components of hot anode exhauststream 31 are typically steam and carbon dioxide with some unreactedresiduals of hydrogen and natural gas. The hot anode exhaust stream 31enters heat exchanger 8 to give up some of its heat to natural gasstream 7, the cooler anode exhaust stream 32 is further cooled in heatexchanger 33 to give up more of its heat to carbon dioxide stream 67 togenerate high temperature carbon dioxide stream 68. The cooler anodeexhaust stream 34, is further cooled in heat exchanger 35 by waterstream 43 to generate low pressure steam streams 44 and 48. The cooleranode exhaust stream 36, is further cooled in heat exchanger 37 byoverhead carbon dioxide stream 62. The cooler anode exhaust stream 38,is further cooled in heat exchanger 6 by natural gas stream 5 and entersseparator 40 to separate and collect the condensed water component ofthe anode exhaust stream 39. The concentrated carbon dioxide anodeexhaust stream 49, exits separator 40 and pressurized by compressor 51,followed by air cooled fin/fan 52. The air cooled concentrated carbondioxide stream 53 is further cooled in heat exchanger 19 by atmosphericair supply stream 18. Atmospheric air supply stream 18 is initiallyprovided by stream 14, which is compressed by compressor 15 to producecompressed air stream 16, and then cooled in an air cooled fin/fan 17.The cooler concentrated carbon dioxide stream 54 is further cooled inheat exchanger 55 by concentrated carbon dioxide gaseous stream 67. Thecolder concentrated carbon dioxide anode exhaust 56 is further cooled inheat exchanger 57 by liquid carbon dioxide stream 66 and further cooledin heat exchanger 4 by expanded natural gas stream 3. The coldconcentrated carbon dioxide anode exhaust stream 59 enters carbondioxide separator 60 where the condensed carbon dioxide is separatedfrom the gaseous fractions. The gaseous cold carbon dioxide stream andunreacted residuals stream 61 enters heat exchanger 55 to give up someof its coolth to anode exhaust stream 54, the warmer stream 62 isfurther heated in heat exchanger 37 by anode exhaust stream 36, theheated gaseous carbon dioxide and unreacted residuals stream 63 is mixedwith air stream 22 at air pre-heater 23 where the unreacted residualsare catalytic oxidized and the oxidant stream 24 is heated to cathode 25temperature. The fuel cell cathode 25 consumes the oxygen from the airand the circulated carbon dioxide from stream 63 to produce carbonateion for transfer through an electrolyte to the fuel cell anode 47. Thehot cathode exhaust stream exits fuel cell cathode 25 through stream 26,mainly nitrogen with residuals of carbon dioxide, water vapour andoxygen, enters heat exchanger 12 to heat fuel cell natural gas feedstream 10 b, the heated natural gas stream 13 is mixed with steam stream45, the mixed stream 46 is fed to the fuel cell anode 47 reformer toproduce hydrogen and carbon dioxide. The cooled cathode exhaust stream27 is further cooled in heat exchanger 28, heating fuel cell anodereformer steam supply stream 44 and the further cooled stream 29 iscooled in heat exchanger 21 by compressed and cooled atmospheric airsupply 20 to air pre-heater 23. The cooled cathode exhaust stream 30 maybe separated downstream to recover nitrogen for other uses.

The recovered water stream 41 from separator 40 enters pump 42 and ispumped into stream 43, routed to heat exchanger 35 and may be used toproduce two steam streams 44 and 48. Steam stream 44 is recycled throughheat exchanger 28 to the fuel cell anode 47 reformer. The other stream48 of steam may be routed to other uses.

The recovered carbon dioxide liquid stream 64 from separator 60 isrouted to pump 65 and pressurized for other process uses. Thepressurized liquid carbon dioxide stream 67 is routed through heatexchanger 33 where it is heated by anode exhaust stream 32. The heatedcarbon dioxide stream 68 is routed for other process uses. The objectiveof the process is; first to recover and separate the components of afuel cell exhaust streams by condensation in counter current heatexchange process configuration, second by pressurizing and heating therecovered liquids in a counter current heat exchange processconfiguration to produce streams for other uses. The innovation is inthe recovery of components and thermal energy from a fuel cell exhauststreams of a fuel cell power generation plant and using these streamswith power generated from the fuel cell 70 to produce petrochemicals atnear zero GHG emissions.

Referring to FIG. 2 , another example is shown, which differs from FIG.1 by routing a portion of natural gas stream 1 through a dedicated gasexpander 200 which reduces the gas pressure to the pressure requirementsfor other uses other than as a fuel cell gas pressure supply. Thedifferent expanded gas pressure supply to other uses stream 201 isfurther heated in heat exchangers 6 to stream 202 and heat exchanger 8to stream 203, which is routed for other process uses. In this example,natural gas stream 9 is not divided into two separate streams as is thecase in FIG. 1 , as stream 203 may be used for similar purposes asstream 11.

There will now be described different examples in which the products ofthe fuel cell 70 in FIGS. 1 and 2 are used to produce petrochemicals.Referring to FIG. 3 , there is shown a process arrangement that may beused to produce syngas for petrochemical processes by the dry reformingprocess. The proposed method uses a carbon dioxide stream 68 which wascondensed, separated, recovered, pressurized and heated from a fuel cellanode exhaust stream 31 (as shown in FIG. 1 ). A natural gas stream 11,preheated by fuel cell anode exhaust stream 31 (as shown in FIG. 1 ), ismixed with preheated carbon dioxide stream 68 in mixer 300. The mixedpreheated mixture of carbon dioxide and natural gas stream 301 is routedto a dry catalytic dry reforming unit 302. The catalytic reaction in dryreforming is an endothermic reaction, electricity generated by the fuelcell 70 is delivered through electrical supply line 303 to dry reformingunit 302 to provide both thermal and motive energy. Some or all of theelectricity 69 produced by the fuel cell 70 may be used to power anelectric furnace or electric heating element devices to support andmaintain an endothermic catalytic reaction, which may be used to enablesthe production of syngas at near zero GHG emissions in dry reformingunit 302. The produced syngas stream 304 of carbon monoxide and hydrogencan then be routed to other downstream catalytic processes such asacetic acid production, Fisher Tropsch processes, etc.

Those knowledgeable in the art will recognize and appreciate the manyvariations and use of this syngas produced by the proposed dryreforming, where both motive and electrical energy can be additionallysupplied by a fuel cell 70 enabling these processes to producepetrochemicals at near zero GHG emissions.

Referring to FIG. 4 , another example of a process arrangement is shown,which differs from FIG. 3 in that it produces methanol by steam-carbondioxide reforming of natural gas (methane). The proposed method uses asteam stream 68, which was produced by condensing, separating,recovering, pressurizing and heating it from a fuel cell anode exhauststream 31 (as shown in FIG. 1 ). The steam stream 68 is added to mixer400 along with preheated carbon dioxide stream 68 and preheated naturalgas stream 11. The mixture stream of steam carbon dioxide and naturalgas 401 is routed to methanol catalytic reactor unit 402, which producesmethanol stream 404. The catalytic reaction in dry reforming is anendothermic reaction, electricity generated by the fuel cell 70 isdelivered through electrical supply line 403 to methanol catalyticreactor unit 402 to provide both thermal and motive energy.

Those knowledgeable in the art will recognize and appreciate the featureof this method, where the reactants and energy produced by a fuel cellenables this process to produce methanol at near zero GHG emissions.

Referring to FIG. 5 , another example of a process arrangement is shown,in which a variation on the uses of recovered exhaust streams from thefuel cell 70 is designed to produce additional petrochemical products.The water and/or vapour stream 48 produced by the fuel cell 70 is routedto electrolyzer 500 to generate oxygen and hydrogen. The electricityrequirements of electrolyzer 500 are supplied by electricity generatedin the fuel cell power line 69 and routed to electrolyzer 500 throughpower line 501. The oxygen generated at electrolysis unit 500 routedthrough line 502 to auto thermal oxidation unit 503 to react withnatural gas stream 11 and carbon dioxide stream 504 to produce syngasstream 506. The electrical energy requirements of the auto thermaloxidation unit 503 are supplied by fuel cell generated power line 69through power line 505. The auto thermal reforming syngas product 506may be routed to other catalytic units to produce petrochemicals and/orfuels. The hydrogen produced by electrolysis unit 500 may be routedthrough hydrogen stream 507 to an ammonia unit 509, and a portion may bediverted through line 508 for other uses. Nitrogen stream 30 producedand recovered from the fuel cell cathode stream 26 (as shown in FIG. 1 )is routed to ammonia unit 509 for a catalytic reaction with hydrogenstream 507 to produce ammonia. The energy requirement of ammonia unit509 is supplied through line 510. The ammonia stream 512 may be routedto storage or for other catalytic process through stream 511. Theammonia stream 511 may be routed to another catalytic unit 513, a ureaunit. The carbon dioxide required for the production of urea may besupplied by fuel cell produced carbon dioxide stream 68, through line514. The energy requirement for the production of urea is supplied byelectricity generated by the fuel cell 70 through power line 515. Theurea produced is routed to storage through line 516.

Those knowledgeable in the art will recognize and appreciate the featureof this method where the reactants and energy produced by a fuel cellenables various processes to produce petrochemical feedstock andproducts from two inputs natural gas and atmospheric air at near zeroGHG emissions, in addition to the examples discussed above.

Fuel cells are presently in operation in sizes up to 59 MW and easilyscalable to larger sizes. These power generation fuel cell sizes producecarbon dioxide, water and nitrogen streams as a byproduct of powergeneration that permits the production of petrochemicals at near zeroGHG emissions using established and proven catalytic processes. In orderto produce petrochemicals, these proposed processes use the highlyconcentrated, high quality streams of water, carbon dioxide andnitrogen. In addition, the thermal energy of the fuel cell exhauststreams is fully recovered to enhance the energy efficiency of theseprocesses. Moreover, the use of produced electrical power to provide thethermal energy requirements of these catalytic processes throughelectric furnaces and or electric heating elements allows for theproduction of petrochemical products at near zero GHG emissions. As canbe appreciated, the proposed methods provide many stream combinations toachieve desired petrochemicals feedstocks and or products. As anexample, the auto thermal reformer can be operated with either a supplyof carbon dioxide, methane and oxygen as shown, or with a supply ofsteam, methane and oxygen to achieve a different syngas ratio of H₂:COto meet a desired petrochemical feedstock or product. Additionally, themethod also provides the means to reform higher molecular weighthydrocarbon fractions such as ethane, propane, etc., and/ordehydrogenation. The various combinations of mixing hydrocarbon streamswith fuel cell derived energy (electrical+thermal) and carbon dioxide,nitrogen and water provide a method of producing petrochemicalfeedstocks and or products at near zero GHG emissions.

The proposed method also permits the efficient recovery of componentsand thermal energy from a fuel cell anode exhaust stream at a powergeneration plant to produce supercritical fluids.

Referring to FIG. 6 , there is shown a further example of the manypossible methods that can be integrated with a fuel cell to producepetrochemical feedstocks and products two single inputs; natural gas andatmospheric air.

As indicated above on the many variations on integrating the fuel celland its outputs with a natural gas stream, FIG. 6 depicts a processmodel where a rich natural gas stream is processed in unit 601 toproduce a methane stream 1, an ethane stream 602 and a propane stream603, it is understood although not shown that butane streams can also beproduced in unit 601 and routed to other uses including syngasproduction or and fuels production. The gas processing unit 601 can be agas processing unit, a gas straddle plant, or the like. The ethanestream 602 is mixed with carbon dioxide stream 604, the mixed stream 605is routed to catalytic unit 606 for the catalytic dehydrogenation ofethane. The produced ethylene stream 607 is routed to petrochemicalunits shown as 608 that can be operated to produce various products suchas polymers, stream 609 or chemicals such as ethylene glycol in stream610.

The propane stream 603 is mixed with carbon dioxide stream 611, themixed stream 612 is routed to catalytic unit 613 for the catalyticdehydrogenation of propane. The produced propylene stream 614 is routedto petrochemical units, shown as 615, that can be operated to producevarious products such as polymers as stream 616 or fibres as stream 617.

A further example of the production of a petrochemical feedstock is theuse of syngas stream 620 produced in the dry methane reformer unit 302to feed a catalytic acetic acid unit 621 to produce acetic acid asstream 622. Moreover is the integration of syngas produced in the autothermal reforming unit 503, through stream 506 to a Fisher Tropsch unit618 to produce synthetic fuels stream 619.

Referring to FIG. 7 , a further example of a method of producingpetrochemicals is shown. In this example, petrochemicals may be producedat a separate location using one or more exhaust products produced fromthe fuel cell.

In this example, a portion 10 b of a natural gas stream 10 passesthrough a heat exchanger 12 and enters the fuel cell anode section 47through stream 46. Other process such as those depicted using stream 44and heat exchanger 28 may also be employed in processing inputs to fuelcell 70. Fuel cell 70 is operated to produce one or more exhauststreams, such as hot anode exhaust stream 31, which includes carbondioxide and water, and hot cathode exhaust stream 26, which includes anitrogen-containing gas. Fuel cell 70 also produces an electricitystream 69. As shown, hot anode exhaust stream 31 is separated in aprocessor 702 into stream 704 for carbon dioxide and stream 706 for thewater. Processor 702 may take a number of forms as are known in the art,and examples of which are described herein. At least one of theseexhaust streams 704, 706, 69, and 29 are captured for furtherprocessing. As shown, carbon dioxide stream 704 is captured forprocessing, however, it will be understood that other streams may alsobe captured and used in a variety of combinations. Carbon dioxide stream704 may be stored or transported to a processing facility as shown at708, and may not be processed on site. Carbon dioxide stream 704 mayalso be treated, such as by preheating or pressurizing. The capturedexhaust stream is then provided through stream 710 to a mixer 300 whereit is mixed with a stream of natural gas 11. The mixture of carbondioxide and natural gas 301 is then provided to a reactor 712 in whichone or more petrochemical streams 714 are produced. The reaction betweencarbon dioxide and natural gas may involve methods described herein, orother methods as are known in the art. Additional reactants or energyinputs may be provided to reactor 712 at 716. These additional reactantsor energy may include the outputs from 706, 69, and 29, or may includeinputs from other sources. It will be understood that water stream 706and nitrogen-containing gas stream 29 may also be transported for use inreactor 712, or may be transported to other locations or for otherpurposes. It will be understood that the carbon dioxide produced by thefuel cell may contain other carbon-containing components, and the exactcomposition will depend on the operation of the fuel cell.

Referring to FIG. 8 , there is shown a method of recovering a fuel cellanode exhaust stream of water and carbon dioxide and its thermal energyto mix and react with natural gas or methane to produce methanol in adirect methane to methanol tri reforming process. In the depictedexample, natural gas and atmospheric air are shown as being delivered tofuel cell 70 and the recovered exhaust streams are separated andconditioned as described above.

Once obtained, the heated carbon dioxide stream 68 is then routed to amixing chamber 105 to mix with preheated natural gas stream 204 andsteam stream 48. A supply of natural gas stream 1 is routed through gasexpander/generator 200 to supply a natural gas stream 201 to a trireformer methane reactor 109. A refrigerant gas stream 201 is producedby expanding a high pressure natural gas stream 1 through gas expander200. The expanded natural gas stream 201 is heated first in heatexchanger 4 by stream 58, the heated stream 202 followed by furtherheating in heat exchanger 6 by stream 38, the heated stream 203 isfurther heated in heat exchanger 8 by stream 31. The heated stream 204enters mixing chamber 105 where it is mixed with heated carbon dioxidestream 68 and steam stream 48. The mixed stream 106 is heated toreaction temperature on an on-line electric heater 107 by electricitysupplied through power line 108. The heated mixture of natural gas,carbon dioxide and steam is routed through line 109 to catalytic reactor110 to produce a methanol stream 112. A power line 111 provideselectricity to meet the energy requirements of unit 110. The objectiveof the process is first, to recover and separate the components of afuel cell exhaust streams by condensation in counter current heatexchange process configuration; and second, by pressurizing and heatingthe recovered liquids in a counter current heat exchange processconfiguration to produce streams of carbon dioxide and water to mix andreact with natural gas to produce methanol. The example described abovediscloses a process that is able to recover components and thermalenergy from exhaust streams of a fuel cell power generation plant, anduses these streams by mixing them with natural gas and bringing thesemixed and heated components to reaction temperature by using powergenerated from the fuel cell to produce methanol at near zero GHGemissions.

Referring to FIG. 9 , a modification of the process of FIG. 8 is shown.The process arrangement differs from FIG. 8 by being able toindividually control each reactant flowrate and stream temperature tooptimum operating conditions before mixing. After mixing, the optimumreaction temperature of the mixture is controlled by an on-line electricheater 911 before entering the reactor 914. The proposed method uses asteam stream 48 which was produced by condensing, separating,recovering, pressurizing and heating it from a fuel cell anode exhauststream 31 (as shown in FIG. 8 ). The flow controlled preheated steamstream 48 is heated to optimum reactant temperature by an on-lineelectric heater 905. The electricity to heater 905 is supplied by powerline 907. The flow controlled heated steam stream 906 enters mixingchamber 902. The flow controlled preheated carbon dioxide stream 68 isfurther heated to optimum temperature conditions in on-line electricheater 903. The electricity supply to heater 903 is provided by powerline 908. The flow controlled heated carbon dioxide stream 904 entersmixing chamber 902. The flow controlled preheated natural gas stream 104is heated to optimum reactant temperature by an on-line electric heater900. The electricity to heater 900 is supplied by power line 909. Theflow controlled heated steam stream 901 enters mixing chamber 902. Themixture of natural gas, carbon dioxide and steam exits mixing chamber902 through line 910 and enters on-line electric heater 911 to heat themixture to optimum reactor temperature operating conditions. Theelectricity to heater 911 is supplied by power line 912. The temperaturecontrolled mixture stream 913 enters reactor 914 to produce methanol.The electricity required for reactor unit 914 operations is supplied bypower line 915. The produced methanol stream exits reactor unit 914 fordistillation and or storage.

To those knowledgeable in the art will recognize and appreciate thefeature of this method were the reactants and energy produced by a fuelcell enables this processes to produce methanol at near zero GHGemissions.

To those knowledgeable in the art will recognize and appreciate thefeature of this method were the reactants and energy produced by a fuelcell enables each reactant stream to be rationed and temperaturecontrolled for optimum operating reactor conditions. The electricalenergy supply produced in the fuel cell allows for methanol to beproduced at near zero emissions. Moreover, those knowledgeable in theart will appreciate the efficiency of on-line electric heating versusthe typical gas operated furnaces. The on-line electric heaters can alsobe an electric furnace. The ability to control the flow and temperatureof each reactant before and after mixing the reactants allows foroperations optimization to maximize the process efficiency.

Referring to FIG. 10 , another example is shown that differs from FIG. 8by compressing the natural gas feed supply in a compressor 1000 ifrequired to meet a TRM reactor operating at higher pressures. The higherpressure requirements for the carbon dioxide and water reactants aresupplied by pumps 65 and 42 respectively. The proposed method uses anatural gas stream 1 entering compressor 1000 and pressurized to TRMoperating pressure. The compressed natural gas stream 1001 is pre-heatedin heat exchanger 8 by the anode exhaust stream 31. The preheatednatural gas stream supply to the TRM 1002 enters mixing chamber 105 tomix with reactants carbon dioxide stream 68 and steam stream 48.

Referring to FIG. 11 another configuration is shown in which a fuel cellanode exhaust stream of carbon dioxide and steam are mixed with naturalgas or methane to produce methanol in a direct methane to methanol trireforming process. Other possible design choices relative to the examplein FIG. 11 are also depicted. One suitable type of fuel cell may includethe Direct Fuel Cell (DFC) manufactured by Fuel Cell Energy in the USA,which have been available since 2003. One known DFC power generationplant is a 59 MW, built in South Korea. A major advantage of a DFC powergeneration plant versus standard power generation combustion processplants is the separated and highly concentrated mass flow rate of theexhaust gas streams allowing for ease of recovery and use versus acombustion process.

In this example, the components and thermal energy in an exhaust stream31 from a fuel cell 70 that is used as a power generation plant aremixed with natural gas, and the mixture is conditioned to a requiredreaction temperature for a TRM unit by using power generated from thefuel cell. The TRM is then used to produce methanol at near zero GHGemissions.

Natural gas is delivered from main transmission pipeline through stream1 and enters expander/generator 2, which reduces the pressure from themain transmission pipeline pressure to meet the pressure of fuel cellinlet pressure in stream 3. This also produces cold temperatures instream 3, as the temperature of stream 3 is decreased from 1.5 to 2degrees Celsius for every 15 psi pressure drop across gas expander 2.The cold natural gas stream 3 enters TRM unit 1110 to provide processcooling through stream 1112 in the TRM unit 1110. The natural gas stream10 is split into two streams: stream 10 a is a supply of natural gasthat is provided to catalytic air heater 23, and stream 10 b is a supplyof natural gas that is supplied to fuel cell 70. Natural gas fuel cellsupply stream 10 b is heated in heat exchanger 12 by cathode exhauststream 27. The heated fuel cell natural gas stream 13 is mixed withsteam stream 45 to produce mixed stream 46, which enters anode section47. At fuel cell anode 47, the natural gas/steam stream 46 is firstreformed to produce hydrogen and carbon dioxide, where the hydrogen isproduced through an electrochemical reaction with a carbonate ionproduced in cathode 25 and transferred through an electrolyte layer tothe anode 47, produces electricity in line 69, and a hot anode exhauststream 31. The carbonate ion produced in cathode 25 and transferredthrough a fuel cell electrolyte layer into anode 47 is converted back tocarbon dioxide in the electrochemical reaction. The main components inhot anode exhaust stream 31 are steam and carbon dioxide, with someunreacted residuals of hydrogen, carbon monoxide and natural gas. Thehot anode exhaust stream 31 is split into streams 1114 and 1116. Stream1114 is a recycling stream that supplies carbon dioxide to the cathodeand mixes with stream 24. The mixed stream 1118 enters cathode section25. The fuel cell cathode 25 consumes the oxygen from the air and thecirculated carbon dioxide supplied by stream 1114 to produce a carbonateion which is transferred through an electrolyte to the fuel cell anode47. The hot cathode exhaust stream exits fuel cell cathode 25 throughstream 26, made up mainly of nitrogen with residuals of carbon dioxide,water vapour and oxygen, enters heat exchanger 28 to heat steam stream44. Steam stream 44 in this example may be from any suitable source ofsteam. The heated steam stream 45 is mixed with natural gas stream 13,and the mixed stream 46 is fed to the fuel cell anode 47 reformer toproduce hydrogen and carbon dioxide. The pre-cooled cathode exhauststream 27 is further cooled in heat exchanger 12 as it heats fuel cellanode reformer natural gas supply stream 10 b. The cathode exhauststream 29 is further cooled in heat exchanger 21 by atmospheric airsupply stream 16 to air pre-heater 23. The cooled cathode exhaust stream30 may be separated downstream to recover nitrogen for other uses. Theair supply to the fuel cell cathode section 25 is provided byatmospheric air stream 14 through compressor 15 to reach the requiredoperation pressure. The compressed air stream 16 is preheated in heatexchanger 21 and preheated, compressed air stream 22 is routed tocatalytic burner 23 to meet the temperature requirements of fuel cellcathode 25. The heated air and flue gas stream mixes with anode exhaustrecycling stream 1114 and enters the fuel cell cathode. The balance ofanode exhaust stream 31, stream 1116 is routed to a jet pump 1120 to mixwith natural gas and conditioned to react in the TRM unit.

A portion of natural gas stream 1 is routed through gasexpander/generator 1122 to supply a natural gas stream 1124 to TRM unit1110. The natural gas stream 1124 is cooled as it passes throughexpander 1122 and the pressure is reduced from the pressure in stream 1.The expanded natural gas stream 1124 provides process cooling to the TRMunit through stream 1126. The heated natural gas stream 1128 enters jetpump 1120 to provide the motive force to drawn in the cathode exhauststream 1116, a mixture of mainly carbon dioxide and steam. Thepressurized mixture of natural gas, carbon dioxide, steam and fuel cellresiduals exits jet pump 1120 through stream 1130 into an on-lineelectric heater 1132, the heat is supplied by electrical line 1134,routed from line 69, to optimize the temperature of mixture stream 1136to the TRM unit 1110 and produce methanol. The pressure for stream 1136is controlled by the pressure letdown of expander/generator 1122 toarrive at an operating pressure for TRM unit 1110. An additional powerline 1138 may be used to export excess power to other users, while powerlines 1134 and 1140 deliver electricity to supply the power requirementsof TRM unit 1110. As can be seen, the process mixes the fuel cell anodeexhaust stream with natural gas and conditions the mixture to therequired operating pressure and temperature conditions to react in a TRMunit 1110 to produce methanol. The produced methanol is then routed tothrough line 1142, for storage or transport.

Referring now to FIG. 12 , another process that produces methanol isshown. The process arrangement differs from FIG. 11 in that the TRM unit1110 operates under negative pressure versus positive pressure as shownin FIG. 11 . Natural gas supply stream 1128 is mixed with fuel cellcathode exhaust stream 1116 in mixing unit 1210. The mixed stream 1130enters on-line electric unit 1132 where it is heated to a desiredmixture temperature and output as heated stream 1136 before entering TRMunit 1110 as a reaction stream. The negative pressure is controlled bycompressor and/or vacuum pump 1214 through stream 1212, which is thenrouted back to TRM unit 41 through stream 1216. This proposed method isan alternative mode of TRM unit operation at negative pressures versuspositive operating pressures as shown in FIG. 11 .

Those skilled in the art will recognize and appreciate the alternativefeature of this method, where the reactants and energy produced by afuel cell enables this process to produce methanol at near zero GHGemissions. Moreover, those skilled in the art will appreciate theefficiency of on-line electric heating versus the typical gas operatedfurnaces, although gas operated furnaces may also be used. The on-lineelectric heaters may also be an electric furnace. The ability to controlpressure and temperature before and after mixing the reactants allowsfor operations optimization to maximize the process efficiency.

Referring to FIG. 13 , another process arrangement is depicted, whichdiffers from FIG. 11 and FIG. 12 in that the TRM unit 1110 has abalanced operating pressure to meet optimum operating conditions in acatalytic or non-catalytic process. The positive pressure is supplied byjet pump 1120 which draws in the cathode exhaust stream 13 to form theTRM mixture stream and compressor and or vacuum pump 1214 provides thebalance pressure of the process circuit from stream 1130 to stream 1212.

Referring to FIG. 14 , another process arrangement is depicted, whichdiffers from FIG. 11 in that natural gas supply expanders/generators 2and 1122 are replaced by JT valves 1410 and 1412, respectively, tocontrol the natural gas pressure to the fuel cell and TRM unit 1110. Inthis mode of operation the cold temperatures generated in streams 3 and1124 are not as cold, and hence less cooling from these streams will beavailable to TRM unit 1110. Moreover, there will not be power generatedas in expander/generators 2 and 1122.

Referring to FIG. 15 , another process arrangement is depicted, whichdiffers from FIG. 11 in that the pressure in a natural gas supply stream1510 is increased by compressor 1512 prior to the natural gas supplyline 1 and prior to expanders/generators 2 and 1122. This allows anotheroption to meet the pressure or cooling requirements of the TRM unit1110.

Referring to FIG. 16 , another process arrangement is depicted, whichdiffers from FIG. 11 in that natural gas supply stream 1610 to the TRMunit provides for higher operating pressures if desired. In this processarrangement the TRM unit operating pressure is determined by the gaspressure supplied by stream 1610. If additional pressure is required instream 1610 a booster compressor can be added to this stream.

Referring to FIG. 17 , another alternative is shown, in which thepressure of the anode exhaust stream 1116 is boosted by a compressor1710, and the compressed anode exhaust stream 1712 is then mixed withnatural gas stream 1128 in mixer 1210.

Fuel cells are presently in operation in sizes up to 59 MW and easilyscalable to larger sizes. These power generation fuel cell sizes producecarbon dioxide, water and nitrogen streams as a by-product of powergeneration that permits the production of methanol at near zero GHGemissions using established and proven catalytic processes. The proposedprocess produces methanol by beneficially using highly concentrated,high quality streams of water and carbon dioxide that are flowcontrolled at optimum ratios and temperature controlled at optimumtemperatures to maximize reactor efficiency. In addition, the thermalenergy of the fuel cell exhaust streams is fully recovered to enhancethe energy efficiency of the process due to its use as a preheater.Moreover, the use of produced electrical power to provide the thermalenergy requirements of direct methane to methanol process throughon-line electric heaters, electric furnaces and or electric heatingelements to allow for the production of methanol at near zero GHGemissions. As can be appreciated the proposed method provides forvarious heat exchangers orientation to maximize heat recovery andefficiency of the fuel cell exhaust streams, recovered exhaust streamcomponents and natural gas streams.

Those skilled in the art will recognize and appreciate the feature ofthe shown methods where the reactants and energy produced by a fuel cellenables the production of methanol from two inputs natural gas andatmospheric air at near zero GHG emissions. In particular, it will beapparent that this process is applicable to a wide range of fuel cellexhaust streams.

It will be understood that, while the process described herein teaches asingle source for each of the components used in the reaction, thatalternatives may involve other sources of reactants. For example, theexhaust components as described herein may be supplemented with carbondioxide and water or other components from other sources. In addition,the natural gas may be provided separately from the fuel stream of thefuel cell. Other modifications may also be made in line with theteachings described above.

Those knowledgeable in the art will recognize and appreciate thefeatures of the shown methods allow the reactants and energy produced bya fuel cell to enable various processes that produce petrochemicalfeedstock and products from two inputs into the fuel cell, i.e. naturalgas and atmospheric air, at near zero GHG emissions. The methodsdescribed allow for one or more components of a fuel cell exhaust streamto be used to produce petrochemicals, and may allow for other outputs ofthe fuel cell to be used in the petrochemical production process, or tobe diverted to other processes or for other purposes. This process maybe adapted to any suitable fuel cell exhaust streams.

In this patent document, the word “comprising” is used in itsnon-limiting sense to mean that items following the word are included,but items not specifically mentioned are not excluded. A reference to anelement by the indefinite article “a” does not exclude the possibilitythat more than one of the element is present, unless the context clearlyrequires that there be one and only one of the elements.

The scope of the claims should not be limited by the preferredembodiments set forth in the examples, but should be given a broadpurposive interpretation consistent with the description as a whole.

What is claimed is:
 1. A method of producing petrochemicals using ahydrocarbon fuel cell, comprising the steps of: operating the fuel cellto produce electricity, thermal energy, and an exhaust stream, theexhaust stream comprising at least a carbon-containing gas and water,the fuel cell receiving a fuel stream of natural gas and a stream ofatmospheric air as inputs; heating a reactant stream of natural gasusing some or all of the electricity, some or all of the thermal energy,or a combination thereof to produce a heated reactant stream of naturalgas; and combining at least a portion of the exhaust stream with theheated reactant stream of natural gas into a reactor input stream, andreacting the reactor input stream in a reactor to produce one or morepetrochemical streams.
 2. The method of claim 1, wherein thecarbon-containing gas and the water are produced from an anode of thefuel cell.
 3. The method of claim 1, wherein the exhaust stream furthercomprises a nitrogen-containing gas produced from a cathode of the fuelcell.
 4. The method of claim 1, wherein at least a portion of thethermal energy is carried by the exhaust stream.
 5. The method of claim4, wherein the thermal energy is used to preheat the reactant stream ofnatural gas.
 6. The method of claim 1, wherein the one or morepetrochemical streams comprises one or more petrochemicals selected froma group consisting of: synthesis gas, methanol, ammonia, urea, polymers,prepolymers, hydrocarbon fuels, acetic acid, and glycol.
 7. The methodof claim 1, further comprising the step of separating thecarbon-containing gas and the water into separate streams using heatexchangers and phase separators.
 8. The method of claim 1, wherein thereactant stream of natural gas and the at least a portion of the exhauststream is preconditioned in heat exchangers using the thermal energyproduced by the fuel cell.
 9. The method of claim 1, further comprisingthe step of powering at least one of material handling equipment andheating equipment of the reactor using electricity produced by the fuelcell.
 10. The method of claim 1, wherein the reactant stream of naturalgas comprises a slipstream of the fuel stream of natural gas.
 11. Themethod of claim 1, wherein substantially all of the carbon in thecarbon-containing gas is consumed in the reactor.
 12. The method ofclaim 1, wherein the reactor conducts two or more reactions in parallelor in series.
 13. The method of claim 1, wherein the at least a portionof the exhaust stream is mixed with the reactant stream of natural gasupstream of the reactor, the exhaust stream comprising a heated streamof carbon-containing gas and water vapor.
 14. The method of claim 13,wherein the reactor is a tri-reform reactor (TRM) that producesmethanol.
 15. The method of claim 14, wherein the TRM is cooled by anexpanded stream of natural gas, the reactant stream of natural gas beingderived from the expanded stream of natural gas.